Vibration-transmission connection for talking-machines



M. 0. HOPKINS. VIBRATION TRANSMISSION CONNECTION .FOR TALKING MACHINES.

APPLICATION FILED JUNE 7, I920.

Patented Sept. (8, 1921..

III A M fifmaw MARCUS C. HOPKINS, OF CHEVY CHASE, DISTRICT OF COLUMBIA.

VERATION-TRANSMISSION CONNECTION FOR TALKING-MACHIN ES.

Specification of Letters Patent.

Patented Sept, 6, 1921.

Application filed June 7, 1920. Serial No. 387,029.

T allcolwm it may concern:

Be it known that I, MARCUS C. HOPKINS, a citizen of the United States ofAmerica, and residing at 3777 Oliver street, Chevy Chase, District ofColumbia, have invented certain new and useful Improvements inVibration-Transmission Connections for Talking-Machines, of which thefollowing is a specification.

This invention relates to vibration-transmission connections for talkingmachines, such as are interposed between the stylus holder and thediaphragm to transmit to the latter the vibrations set up by the passageof the stylus along the phonic line or sound groove'of a record duringplaying.

The invention has special reference to talking machines of the typedisclosed inmy prior Patent No. 1,271,527, granted July 2, 1918, inwhich the usual sound-box and tone arm are replaced by a swinging armwhich moves horizontally across the record and carries at its rear end alarge conical or equivalent diaphragm of vibratile material, the frontend of the arm having a stylus holder attached directly to it. Theswinging arm is made hollow or tubular, and through it extends atransmission element which is connected at one end to the stylus holderand at the other end to the apex of the diaphragm, so that thevibrations to which the transmission element is subjected are exertedupon the diaphragm which is thereby caused to vibrate piston-fashionand, in consequence, acts to regenerate the original soundwaves in theirinitial tonal strength and quality in free, unconfined atmospheric air.

According to the earlier construction; the transmission element had theform of a wire or equivalent member which was originally placed undertension by suitable devices, but was subsequently utilized in anuntensioned condition. It was also proposed to replace the wire rod by atwo-part element comprising metallic and non-metallic sectlons,prefcrably brass or steel and ebony, the purpose being to deaden bymeans of the wooden section'the special vibrations developed as acharacteristic of the metal.

I have now found, however, that I can obtain a reproduction possessing amuch greater degree of brilliancy and sharpness, and with much lessblasting and chattering, by employing, instead of the forms previouslyused, a transmission element which consists of a metal rod, preferablybrass,

having a relatively-large diameter as compared with the former devicesand extremely thin walls The ends of this rod are reduced or narrowed,and are attached, one to the apex of the diaphragm and the other to thebase portion of the stylus holder, which latter is preferably mountedupon knife bearings provided on the cap at the front end of the swingingarm, instead of being attached to a leaf spring connected to the arm endas was formerly proposed.

An embodiment of the invention is illustrated in the accompanyingdrawing; but it is to be understood that no limitation to the precisestructural details of such disclosure is contemplated, as the inventionis susceptible of modifications and changes within its scope ashereinafter claimed.

In the drawing:

Figure 1 is a part-sectional side elevation of a diaphragm and carrierarm and associated parts of the general type disclosed in myabove-identified patent.

Fig. 2 is an enlarged cross-section on line 2-2, Fig. 1.

eferring more particularly to the drawing, 5 indicates generally aconical diaphragm constructed of paper or other suitable stiff andvibratile sheet material and mounted by means of a spider 6 on the rearend of a hollow arm or tube 7 which is arranged to move horizontallyacross the record and which is provided at its front end with a stylusholder 8. The conical diaphragm has, by preference, the dimensionsspecified in my previously identified patent, and to its apex there isconnected one end of the vibration-transmission element 9, the other endof which is connected to the stylus holder. The latter is here shown asof the type usually employed in the standard Path machines, andcomprises a chuck 10 adapted to receive the usual sapphirepointed stylus11 for' playing vertical-cut records; but it will be understood thatsuch stylus can beremoved and replaced by a steel, or other stylus whena lateral-cut rec'- ord is to be played, in which case the arm 7 isturned through an angle of 90 and the stylus holder itself thereafteradjusted. The feature of setting or adjusting the arm and stylus holderfor universal playing purposes forms no part of'the present in.-vention, however, and consequently requires no special description norillustration; it is fully disclosed in Letters Patent No. 1,218,083,granted October 7, 1919, to Fredrick E. Jose, to which reference may behad for a complete understanding thereof. The base or cross-piece 12 ofthe holder is fulcrumed on knife-edge pivots or bearings 13 carried bythe cap 14 onthe front end of the arm, and is subjected to the pressureof tension springs 15 controlled by screws 16.

The carrier arm or tube 7 is provided a Slight distance in front of thehub of spider 6 with a pair of spaced rings 17, which are rigidlysecured to it and between which there is interposed a wider ring orsleeve 18 in which the arm rotatably fits to enable the above-mentionedadjustment of said arm from either of its two playing positions to tothe other. This sleeve 18 is pivotally supported by means of a pair ofpins 19 (only one of which appears) in the upper portions of the arms ofa vertically-disposed yoke 20,- the stem of which fits rotatably in asleeve bearing (not shown.) forming part of a supporting bracket adaptedto be fastened to the cabinet of the machine at some suitable point. Theabove described mounting therefore constitutes, in effect, a universaloint which provides for swinging movement'of the arm in both horizontaland vertical planes, as will be understood.

The transmission element, which constitutes the most important featureof my invention, consists ofa hollow metal rod or tube, preferablyconstructed of brass and having very thin Walls. It is arrangedeccentrically of the arm bore and has a diameter which is quite large ascompared withthe diameters of the transmission'elements previouslyproposed in connection with machines of this character, as well as thoseused in the ordinary sound-boxes. In practice, it may varyfrOmone-quarter to three-eighths of an inch in diameter, whereas therods or wires or vibrator bars previously used had a diameter less thanoneeighth of an inch; while the'arm itself has a diameter ofapproximately one inch. As

shown, the diameter of the rod is constant, excepting at the ends of therod where it is considerably reduced to permit its connection to theapex of the diaphragm and the base or cross-piece 12 of the stylusholder. At its point of attachment to the said crosspiece, it is, infact, narrowed and flattened out to form a virtual knife-edge 21, whichis received in a notch or kerf 22 in the crosspiece.

The reduced portion at the rear end of the transmission rod ispreferably formed by a plug 23 which is threaded into the rod end and iscontracted centrally as at 24, as shown; such construction affording therequisite vibratory movements of the rod which would otherwise be toorigid to vibrate properly.

I claim as my invention:

1. A talking machine element for transmitting vibrations from a stylusholder to a diaphragm, comprising a metal tube having extremely thinwalls.

2. A talking machine element for transmitting vibrations from a stylusholder to a diaphragm, comprising a thin-walled, tubular metal rodhaving its major portion of constant diameter.

3. A talking machine element for transmitting vibrations from a stylusholder to a diaphragm, comprising a straight tubular metal rod havingits major portion of constant diameter and at least one-end of reduceddiameter.

4. A talking machine element for transmitting vibrations from a stylusholder to a diaphragm, comprising a thin-walled, tubular metal rodhaving its major portion of constant diameter and at least one end ofreduced diameter.

5. A vibration-transmission element for talking machines, comprising athin-Walled, tubular metal rod of relatively large diameter.

In testimony whereof I have aflixed my signature.

MARCUS O. HOPKINS.

